1. Field of the Invention
The present invention generally relates to the field of electronic equipment. More particularly, the present invention relates to the field of voltage regulated power supplies or voltage regulators.
2. Description of the Prior Art
Voltage regulated power supplies or voltage regulators are widely used in electrical and electronics industries.
Today, switchmode regulated power supplies have become commonplace in the computer industry and have the advantage of high power efficiency compared to linear regulators. A prior art switchmode voltage regulator typically consists of a voltage adjuster and a servo loop which operate as follows. An unregulated DC voltage is fed into the voltage adjuster. The voltage adjuster produces a controlled output voltage and receives a control input from the servo loop. The servo loop senses the output voltage of the voltage adjuster and sends a suitable correction signal to the voltage adjuster to cause the output voltage to remain at a predetermined level.
One of the disadvantages of the prior art voltage regulators is that the relatively high output noise of switchmode power supplies has generally prevented their use in analog equipment. Although adding a subsequent filter can make switchmode power supplies suitable for many analog system applications, the additional time delay of the secondary filter can cause instability of the regulation servo loop, especially with remote sensing. In addition, if the servo loop is more heavily compensated to reduce the instability, i.e., the loop filter made slower, the ability to dynamically eliminate rectifier ripple at the output is reduced.
It is desirable to provide a new voltage regulator which can overcome all of the problems of the prior art switchmode voltage regulators, and is suitable for use in more critical systems where excellent regulation and low output noise are required.